Björn Hielscher (AG Linka)

Plant peroxisomes are highly dynamic organelles metabolically interacting with various other compartments of the cell. These interactions consist of essential pathways including fatty acid β-oxidation, photorespiration, phytohormone biosynthesis and immune responses. In photosynthetic active cells the photorespiratory pathway plays a central role. Here, the byproduct of the RubisCO reaction, 2-phosphoglycolate, is further metabolized and recycled under high energy consumption through the use of the three organelles chloroplast, mitochondrion and peroxisome.

It is not surprising, that the dual function of RubisCO is a limiting growth factor in C3 plants especially under high light intensity or drought stress. On the contrary, C4 plants have evolved a cell-dependent CO2 concentrating mechanism to reduce the oxygenation reactions during CO2 fixation. This evolutionary invention lead to a strong decrease in photorespiratory activity in C4 plants accompanied with the reduction of transcripts of photorespiratory enzymes.

Although aspects of the photorespiration process, e.g. subcellular localization and metabolite processing, are well described, the transport mechanism between the participating organelles remains poorly understood. Based on this, we are interested in those genes, which show a strong decrease in transcription in plants using the C4-cycle but are highly expressed in C3 plants. We expect transporters responsible for the transfer of glycolate, glycerate, glycine, serine or other metabolites, which are guided through the peroxisome, to show a similar expression pattern like the photorespiratory enzymes. Transcriptomic data of different Flaveria and Cleome species including C3, C3-C4-intermediate and C4 plants are used to identify candidates for putative peroxisomal transporters. Most promising candidate genes will be analyzed in detail. This will be the basis for further subcellular localization and characterization studies. The knowledge of these transporters will help us to understand the dynamics of the peroxisome as central part of the plant cell.

Starting date: 01.05.2014 / PhD student

Thesis committee members: Nicole Linka,

Mini Academic CV:

  •  2011
    • Bachelor of Science (B. Sc.) at Department of Plant Biochemistry, Heinrich Heine University Düsseldorf
      Thesis: Cloning of a dual-function glycogen synthase/branching enzyme from Galdieria sulphuraria
  • 2013
    • Master of Science (M. Sc.) at Department of Plant Biochemistry, Heinrich Heine University Düsseldorf
      Thesis: Biochemical characterization of a hexose phosphate transporter of the glaucophyte Cyanophora paradoxa and of a putative glycogen synthase of the rhodophyte Galdieria sulphuraria
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Björn Hielscher M.Sc.

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